Transepithelial neutrophil migration is CXCR1 dependent in vitro and is defective in IL-8 receptor knockout mice

Genetic polymorphisms associated with urinary tract infection in children and adults: a systematic review and meta-analysis

INTRODUCTION

The lifetime risk of urinary tract infection is known from first-degree relative studies to be highly heritable. Associations have also been observed across the life course from pediatric urinary tract infection to recurrent urinary tract infection in adulthood, suggesting lifelong susceptibility factors. Candidate gene studies and genome-wide association studies have tested for genetic associations of urinary tract infection; however, no contemporary systematic synthesis of studies is available.

OBJECTIVE

We conducted a systematic review to identify all genetic polymorphisms tested for an association with urinary tract infection in children and adults; and to assess their strength, consistency, and risk of bias among reported associations.

DATA SOURCES AND STUDY ELIGIBILITY CRITERIA

PubMed, HuGE Navigator and Embase were searched from January 1, 2005 to November 16, 2023, using a combination of genetic and phenotype key words.

STUDY APPRAISAL AND SYNTHESIS METHODS

Fixed and random effects meta-analyses were conducted using codominant models of inheritance in metan. The interim Venice criteria were used to assess their credibility of pooled associations.

RESULTS

After removing 451 duplicates, 1821 studies reports were screened, with 106 selected for full-text review, 22 were included in the meta-analysis (7 adult studies and 15 pediatric studies). Our meta-analyses demonstrated significant pooled associations for pediatric urinary tract infection with variation in CXCR1, IL8, TGF, TLR4 and VDR; all of which have plausible roles in the pathogenesis of urinary tract infection. Our meta-analyses also demonstrated a significant pooled association for adult urinary tract infection with variation in CXCR1. All significant pooled associations were graded according to their epidemiological credibility, sample sizes, heterogeneity between studies, and risk of bias.

CONCLUSION

This systematic review provides a current synthesis of the known genetic architecture of urinary tract infection in childhood and adulthood; and should provide important information for researchers analysing future genetic association studies. Although, overall, the credibility of pooled associations was weak, the consistency of findings for rs2234671 single nucleotide polymorphisms of CXCR1 in both populations suggest a key role in the urinary tract infection pathogenesis.

Recurrent urinary tract infection genetic risk: a systematic review and gene network analysis

INTRODUCTION AND HYPOTHESIS

The development of recurrent urinary tract infections (rUTIs) is not completely understood. This review is aimed at investigating the connection between genetics and rUTIs and summarizing the results of studies that have documented variations in gene expression among individuals with rUTIs compared with healthy individuals.

METHODS

A systematic search was conducted in Cochrane, Ovid, and PubMed, limiting the results to articles published between 1 January 2000, and 5 July 2022. Only studies comparing the difference in gene expression between individuals with rUTI and healthy individuals utilizing molecular techniques to measure gene expression in blood or urine samples were included in this systematic review. Gene network and pathways analyses were performed using Cytoscape software, with input data obtained from our systematic review of differentially expressed genes in rUTIs.

RESULTS

Six studies met our criteria for inclusion. The selected studies used molecular biology methods to quantify gene expression data from blood specimens. The analysis revealed that gene expressions of CXCR1 and TLR4 decreased, whereas CXCR2, TRIF, and SIGIRR increased in patients with rUTI compared with healthy controls. The analysis demonstrated that the most significant pathways were associated with TLR receptor signaling and tolerance, I-kappa B kinase/NF-kappa B signaling, and MyD88-independent TLR signaling.

CONCLUSIONS

This systematic review uncovered gene expression variations in several candidate genes and identified a number of underlying biological pathways associated with rUTIs. These findings could shift the treatment and prevention strategies for rUTIs.

Human CXCR1 knock-in mice infer functional expression of a murine ortholog

Targeting CXCR1 and CXCR2 chemokine receptors to block neutrophil migration to sites of inflammation is a promising therapeutic approach for various inflammatory and autoimmune diseases. However, assessing the translational potential of such therapies using mouse models is challenging due to the unclear expression of CXCR1 at the protein level. Although CXCR2 has been well characterized in both mice and humans, the protein-level expression of CXCR1 in mice (mCXCR1) remains controversial. To address this issue, we generated a novel human CXCR1 knock-in (hCXCR1 KI) mouse model in which the transgene is under the control of the native mouse promoter and regulatory elements. Using an anti-human CXCR1 monoclonal antibody (anti-hCXCR1 monoclonal antibody), we found that hCXCR1 was highly expressed on neutrophils in the hCXCR1 KI mice, comparable to levels observed in human neutrophils. This successful expression of hCXCR1 in this mouse model suggests that functional mCXCR1 likely exists. To investigate the functional role of CXCR1, we investigated how antagonizing this receptor using anti-hCXCR1 monoclonal antibody in the arthritis model would affect disease outcomes. Antibody treatment significantly alleviated all signs of joint inflammation. In summary, our newly generated hCXCR1 KI transgenic mice provide a valuable tool to investigate the therapeutic efficacy of small molecules or monoclonal antibodies that antagonize this receptor in neutrophil-mediated pathologies.

Trimethylamine N-Oxide (TMAO) Mediates Increased Inflammation and Colonization of Bladder Epithelial Cells during a Uropathogenic E. coli Infection In Vitro

Urinary tract infections (UTIs) are among the most common infections in humans and are often caused by uropathogenic E. coli (UPEC). Trimethylamine N-oxide (TMAO) is a proinflammatory metabolite that has been linked to vascular inflammation, atherosclerosis, and chronic kidney disease. As of today, no studies have investigated the effects of TMAO on infectious diseases like UTIs. The aim of this study was to investigate whether TMAO can aggravate bacterial colonization and the release of inflammatory mediators from bladder epithelial cells during a UPEC infection. We found that TMAO aggravated the release of several key cytokines (IL-1β and IL-6) and chemokines (IL-8, CXCL1 and CXCL6) from bladder epithelial cells during a CFT073 infection. We also found that CFT073 and TMAO mediate increased release of IL-8 from bladder epithelial cells via ERK 1/2 signaling and not bacterial growth. Furthermore, we showed that TMAO enhances UPEC colonization of bladder epithelial cells. The data suggest that TMAO may also play a role in infectious diseases. Our results can be the basis of further research to investigate the link between diet, gut microbiota, and urinary tract infection.

Convergent copy number increase of genes associated with freshwater colonization in fishes

Copy number variation (CNV) can cause phenotypic changes. However, in contrast to amino acid substitutions and cis-regulatory changes, little is known about the functional categories of genes in which CNV is important for adaptation to novel environments. It is also unclear whether the same genes repeatedly change the copy numbers for adapting to similar environments. Here, we investigate CNV associated with freshwater colonization in fishes, which was observed multiple times across different lineages. Using 48 ray-finned fishes across diverse orders, we identified 23 genes whose copy number increases were associated with freshwater colonization. These genes showed enrichment for peptide receptor activity, hexosyltransferase activity and unsaturated fatty acid metabolism. We further revealed that three of the genes showed copy number increases in freshwater populations compared to marine ancestral populations of the stickleback genus Gasterosteus. These results indicate that copy number increases of genes involved in fatty acid metabolism (FADS2), immune function (PSMB8a) and thyroid hormone metabolism (UGT2) may be important for freshwater colonization at both the inter-order macroevolutionary scale and at the intra-genus microevolutionary scale. Further analysis across diverse taxa will help to understand the role of CNV in the adaptation to novel environments. This article is part of the theme issue 'Genetic basis of adaptation and speciation: from loci to causative mutations'.

A Systematic Review of the (Un)known Host Immune Response Biomarkers for Predicting Recurrence of Urinary Tract Infection

Recurrent urinary tract infections (rUTI) represent a major healthcare and economic burden along with a significant impact on patient’s morbidity and quality of life, even in the absence of well-known risk factors, such as vesicoureteral reflux. Despite numerous attempts to find a suitable therapeutic option, there is no clear benefit of any currently available intervention for prevention of UTI recurrence and its long-term consequences such as hypertension, renal scarring and/or insufficiency. The common treatment practice in many centers around the globe involves the use of continuous low-dose antibiotic prophylaxis, irrespective of various studies indicating increased microbial resistance against the prophylactic drug, leading to prolonged duration and escalating the cost of UTI treatment. Moreover, the rapid appearance of multi-drug resistant uropathogens is threatening to transform UTI to untreatable disease, while impaired host-microbiota homeostasis induced by a long-term use of antibiotics predisposes patients for various autoimmune and infectious diseases. New biomarkers of the increased risk of UTI recurrence could therefore assist in avoiding such outcomes by revealing more specific patient population which could benefit from additional interventions. In this light, the recent findings suggesting a crucial role of urothelial innate immunity mechanisms in protection of urinary tract from invading uropathogens might offer new diagnostic, prognostic and even therapeutic opportunities. Uroepithelial cells detect uropathogens via pattern recognition receptors, resulting in activation of intracellular signaling cascade and transcription factors, which ultimately leads to an increased production and secretion of chemokines, cytokines and antimicrobial peptides into the urinary stream. Emerging evidence suggest that the disturbance of a single component of the urinary tract innate immunity system might increase susceptibility for rUTI. The aim of the current review is to update clinicians and researchers on potential biomarkers of host immune response alterations predisposing for rUTI and propose those well worth exploring further. For this purpose, over a hundred original papers were identified through an extensive PubMed and Scopus databases search. This comprehensive review might enrich the current clinical practice and fill the unmet clinical needs, but also encourage the development of therapeutic agents that would facilitate urinary bacterial clearance by enhancing the host immune response.

Immunomodulation therapy offers new molecular strategies to treat UTI

Innovative solutions are needed for the treatment of bacterial infections, and a range of antibacterial molecules have been explored as alternatives to antibiotics. A different approach is to investigate the immune system of the host for new ways of making the antibacterial defence more efficient. However, the immune system has a dual role as protector and cause of disease: in addition to being protective, increasing evidence shows that innate immune responses can become excessive and cause acute symptoms and tissue pathology during infection. This role of innate immunity in disease suggests that the immune system should be targeted therapeutically, to inhibit over-reactivity. The ultimate goal is to develop therapies that selectively attenuate destructive immune response cascades, while augmenting the protective antimicrobial defence but such treatment options have remained underexplored, owing to the molecular proximity of the protective and destructive effects of the immune response. The concept of innate immunomodulation therapy has been developed successfully in urinary tract infections, based on detailed studies of innate immune activation and disease pathogenesis. Effective, disease-specific, immunomodulatory strategies have been developed by targeting specific immune response regulators including key transcription factors. In acute pyelonephritis, targeting interferon regulatory factor 7 using small interfering RNA or treatment with antimicrobial peptide cathelicidin was protective and, in acute cystitis, targeting overactive effector molecules such as IL-1β, MMP7, COX2, cAMP and the pain-sensing receptor NK1R has been successful in vivo. Furthermore, other UTI treatment strategies, such as inhibiting bacterial adhesion and vaccination, have also shown promise.

Hyperactivation of innate immunity is a disease determinant in urinary tract infections (UTIs). Modulation of innate immunity has promise as a therapy for UTIs. In this Review, the authors discuss potential mechanisms and immunomodulatory therapeutic strategies in UTIs.

Excessive innate immune responses to infection cause symptoms and pathology in acute pyelonephritis and acute cystitis.

Innate immunomodulation therapy is, therefore, a realistic option for treating these conditions.

Targeting excessive innate immune responses at the level of transcription has been successful in animal models.

Innate immunomodulation therapy reduces excessive inflammation and tissue pathology and accelerates bacterial clearance from infected kidneys and bladders in mice.

Innate immunomodulation therapy also accelerates the clearance of antibiotic-resistant bacterial strains.

Human Renal Fibroblasts, but Not Renal Epithelial Cells, Induce IL-1β Release during a Uropathogenic Escherichia coli Infection In Vitro

Understanding how uropathogenic Escherichia coli (UPEC) modulates the immune response in the kidney is essential to prevent UPEC from reaching the bloodstream and causing urosepsis. The purpose of this study was to elucidate if renal fibroblasts can release IL-1β during a UPEC infection and to investigate the mechanism behind the IL-1β release. We found that the UPEC strain CFT073 induced an increased IL-1β and LDH release from renal fibroblasts, but not from renal epithelial cells. The UPEC-induced IL-1β release was found to be NLRP3, caspase-1, caspase-4, ERK 1/2, cathepsin B and serine protease dependent in renal fibroblasts. We also found that the UPEC virulence factor α-hemolysin was necessary for IL-1β release. Conditioned medium from caspase-1, caspase-4 and NLRP3-deficient renal fibroblasts mediated an increased reactive oxygen species production from neutrophils, but reduced UPEC phagocytosis. Taken together, our study demonstrates that renal fibroblasts, but not renal epithelial cells, release IL-1β during a UPEC infection. This suggest that renal fibroblasts are vital immunoreactive cells and not only structural cells that produce and regulate the extracellular matrix.

Activated neutrophils polarize protumorigenic interleukin-17A-producing T helper subsets through TNF-α-B7-H2-dependent pathway in human gastric cancer

RATIONALE

Neutrophils constitute massive cellular constituents in inflammatory human gastric cancer (GC) tissues, but their roles in pathogenesis of inflammatory T helper (Th) subsets are still unknown.

METHODS

Flow cytometry analysis and immunohistochemistry were used to analyze the responses and phenotypes of neutrophils in different samples from 51 patients with GC. Kaplan-Meier plots and Multivariate analysis for the survival of patients were used by log-rank tests and Cox proportional hazards models. Neutrophils and CD4+ T cells were purified and cultured for ex vivo, in vitro and in vivo regulation and function assays.

RESULTS

GC patients exhibited increased tumoral neutrophil infiltration with GC progression and poor patient prognosis. Intratumoral neutrophils accumulated in GC tumors via CXCL6/CXCL8-CXCR1-mediated chemotaxis, and expressed activated molecule CD54 and co-signaling molecule B7-H2. Neutrophils induced by tumors strongly expressed CD54 and B7-H2 in both dose- and time-dependent manners, and a close correlation was obtained between the expressions of CD54 and B7-H2 on intratumoral neutrophils. Tumor-derived tumor necrosis factor-α (TNF-α) promoted neutrophil activation and neutrophil B7-H2 expression through ERK-NF-κB pathway, and a significant correlation was found between the levels of TNF-α and CD54+ or B7-H2+ neutrophils in tumor tissues. Tumor-infiltrating and tumor-conditioned neutrophils effectively induced IL-17A-producing Th subset polarization through a B7-H2-dependent manner ex vivo and these polarized IL-17A-producing Th cells exerted protumorigenic roles by promoting GC tumor cell proliferation via inflammatory molecule IL-17A in vitro, which promoted the progression of human GC in vivo; these effects could be reversed when IL-17A is blocked. Moreover, increased B7-H2+ neutrophils and IL-17A in tumors were closely related to advanced GC progression and predicted poor patient survival.

CONCLUSION

We illuminate novel underlying mechanisms that TNF-α-activated neutrophils link B7-H2 to protumorigenic IL-17A-producing Th subset polarization in human GC. Blocking this pathological TNF-α-B7-H2-IL-17A pathway may be useful therapeutic strategies for treating GC.

Inflammation and Antiviral Immune Response Associated With Severe Progression of COVID-19

Coronavirus disease-2019 (COVID-19) is a novel respiratory disease induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It remains poorly understood how the host immune system responds to the infection during disease progression. We applied microarray analysis of the whole genome transcriptome to peripheral blood mononuclear cells (PBMCs) taken from severe and mild COVID-19 patients as well as healthy controls. Functional enrichment analysis of genes associated with COVID-19 severity indicated that disease progression is featured by overactivation of myeloid cells and deficient T cell function. The upregulation of TLR6 and MMP9, which promote the neutrophils-mediated inflammatory response, and the downregulation of SKAP1 and LAG3, which regulate T cells function, were associated with disease severity. Importantly, the regulation of these four genes was absent in patients with influenza A (H1N1). And compared with stimulation with hemagglutinin (HA) of H1N1 virus, the regulation pattern of these genes was unique in PBMCs response to Spike protein of SARS-CoV-2 ex vivo. Our data also suggested that severe SARS-CoV-2 infection largely silenced the response of type I interferons (IFNs) and altered the proportion of immune cells, providing a potential mechanism for the hypercytokinemia. This study indicates that SARS-CoV-2 infection impairs inflammatory and immune signatures in patients, especially those at severe stage. The potential mechanisms underpinning severe COVID-19 progression include overactive myeloid cells, impaired function of T cells, and inadequate induction of type I IFNs signaling.

Behaviour of Human Oral Epithelial Cells Grown on Invisalign® SmartTrack® Material

Invisalign aligners have been widely used to correct malocclusions, but their effect on oral cells is poorly known. Previous research evaluated the impact of aligners’ eluates on various cells, but the cell behavior in direct contact with aligners is not yet studied. In the present study, we seeded oral epithelial cells (cell line Ca9-22) directly on Invisalign SmartTrack material. This material is composed of polyurethane and co-polyester and exhibit better mechanical characteristics compared to the predecessor. Cell morphology and behavior were investigated by scanning electron microscopy and an optical cell moves analyzer. The effect of aligners on cell proliferation/viability was assessed by cell-counting kit (CCK)-8 and 3,4,5-dimethylthiazol-2-yl-2,5-diphenyl tetrazolium bromide (MTT) assay and live/dead staining. The expression of inflammatory markers and proteins involved in epithelial barrier function was measured by qPCR. Cells formed cluster-like structures on aligners. The proliferation/viability of cells growing on aligners was significantly lower (p < 0.05) compared to those growing on tissue culture plastic (TCP). Live/dead staining revealed a rare occurrence of dead cells on aligners. The gene expression level of all inflammatory markers in cells grown on aligners’ surfaces was significantly increased (p < 0.05) compared to cells grown on TCP after two days. Gene expression levels of the proteins involved in barrier function significantly increased (p < 0.05) on aligners’ surfaces after two and seven days of culture. Aligners’ material exhibits no cytotoxic effect on oral epithelial cells, but alters their behavior and the expression of proteins involved in the inflammatory response, and barrier function. The clinical relevance of these effects has still to be established.

Innate immunity and urinary tract infection

Urinary tract infections are a severe public health problem. The emergence and spread of antimicrobial resistance among uropathogens threaten to further compromise the quality of life and health of people who develop acute and recurrent upper and lower urinary tract infections. The host defense mechanisms that prevent invasive bacterial infection are not entirely delineated. However, recent evidence suggests that versatile innate immune defenses play a key role in shielding the urinary tract from invading uropathogens. Over the last decade, considerable advances have been made in defining the innate mechanisms that maintain immune homeostasis in the kidney and urinary tract. When these innate defenses are compromised or dysregulated, pathogen susceptibility increases. The objective of this review is to provide an overview of how basic science discoveries are elucidating essential innate host defenses in the kidney and urinary tract. In doing so, we highlight how these findings may ultimately translate into the clinic as new biomarkers or therapies for urinary tract infection.

Expression and secretion of the pro‑inflammatory cytokine IL‑8 is increased in colorectal cancer cells following the knockdown of non‑erythroid spectrin αII

Non‑erythroid spectrin αII (SPTAN1) expression is decreased in ~40% of cases of MLH1‑deficient colorectal cancer (CRC). SPTAN1 knockdown reduces cell viability, cellular mobility and cell‑cell contact formation, indicating that the SPTAN1 plays an important role in tumour growth, attachment and in regulating the tumour microenvironment. Changes in the tumour microenvironment can affect the immune response. Therefore, in the present study, proteome arrays were used to analyse the expression of 119 different chemokines and soluble receptors in CRC cell lines in which mutL homologue 1 (MLH1) or SPTAN1 were knocked down. The levels of interleukin (IL)‑8 were significantly increased in the cells in which SPTAN1 was knocked down, both at the mRNA and protein level. ELISA demonstrated that the cells in which SPTAN1 was knocked down secreted increased quantities of IL‑8, and chemotaxis assays revealed the enhanced trafficking of neutrophils, which was induced by media containing higher levels of IL‑8. The IL‑8 receptors, CRCX1 and CRCX2, were expressed in all the cell lines examined; however, their expression was not directly associated with IL‑8 expression. The results of the present study thus demonstrated that CRC cells in which SPTAN1 was knocked down secreted significantly higher levels of IL‑8, which in‑turn increased the migration of neutrophilic granulocytes. As MLH1‑deficient CRC exhibits an increased infiltration of cytotoxic T‑cells and is associated with a decreased SPTAN1 expression, it can thus be hypothesized that CRC with a low SPTAN1 expression may release increased quantities of IL‑8, resulting in increased immune cell infiltration.

Increased ferritin levels in non-transfusion-dependent β°-thalassaemia/HbE are associated with reduced CXCR2 expression and neutrophil migration

Severe bacterial infection is a major complication causing morbidity and mortality in β-thalassaemia/HbE patients. Innate immunity constitutes the first line of defence against bacterial infection. This study aimed to comprehensively investigate the innate immune phenotype and function related to factors predisposing to infection in non-transfusion-dependent (NTD) β°-thalassaemia/HbE patients. Twenty-six patients and 17 healthy subjects were recruited to determine complement activity (C3, C4, mannose-binding lectin and CH50) and surface receptor expression including markers of phagocytosis (CD11b, CD16 and C3bR), inflammation (C5aR) and migration (CD11b, CXCR1 and CXCR2) on neutrophils and monocytes. In addition, phagocytosis and oxidative burst activity of neutrophils and monocytes against Escherichia coli and neutrophil migration were examined. Decreased C3 and surface expression of CD11b and C3bR on neutrophils were found in patients. However, phagocytosis of neutrophils in patients was still in the normal range. Interestingly, patients displayed a significant reduction of surface expression of CXCR2 [1705 ± 217 mean fluorescent intensity (MFI)] on neutrophils, leading to impaired neutrophil migration (9·2 ± 7·7%) when compared to neutrophils from healthy subjects (2261 ± 627 MFI and 27·8 ± 9% respectively). Moreover, surface expression of CXCR2 on neutrophils was associated with splenectomy status, serum ferritin and haemoglobin levels. Therefore, impaired neutrophil migration could contribute to the increased susceptibility to infection seen in NTD β°-thalassaemia/HbE patients.

The nucleic acid binding protein YB-1-controlled expression of CXCL-1 modulates kidney damage in liver fibrosis

Acute kidney injury is a common complication of advanced liver disease and increased mortality of these patients. Here, we analyzed the role of Y-box protein-1 (YB-1), a nucleic acid binding protein, in the bile duct ligation model of liver fibrosis and monitored liver and subsequent kidney damage. Following bile duct ligation, both serum levels of liver enzymes and expression of hepatic extracellular matrix components such as type I collagen were significantly reduced in mice with half-maximal YB-1 expression (Yb1^+/-) as compared to their wild-type littermates. By contrast, expression of the chemokine CXCL1 was significantly augmented in these Yb1^+/- mice. YB-1 was identified as a potent transcriptional repressor of the Cxcl1 gene. Precision-cut kidney slices from Yb1^+/- mice revealed higher expression of the CXCL1 receptor CXCR2 as well as enhanced responsivity to CXCL1 compared to those from wild-type mice. Increased CXCL1 content in Yb1^+/- mice led to pronounced bile duct ligation-induced damage of the kidneys monitored as parameters of tubular epithelial injury and immune cell infiltration. Pharmacological blockade of CXCR2 as well as application of an inhibitory anti-CXCL1 antibody significantly mitigated early systemic effects on the kidneys following bile duct ligation whereas it had only a modest impact on hepatic inflammation and function. Thus, our analyses provide direct evidence that YB-1 crucially contributes to hepatic fibrosis and modulates liver-kidney crosstalk by maintaining tight control over chemokine CXCL1 expression.

Glucocorticoids inhibit macrophage differentiation towards a pro-inflammatory phenotype upon wounding without affecting their migration

Glucocorticoid drugs are widely used to treat immune-related diseases, but their use is limited by side effects and by resistance, which especially occurs in macrophage-dominated diseases. In order to improve glucocorticoid therapies, more research is required into the mechanisms of glucocorticoid action. In the present study, we have used a zebrafish model for inflammation to study glucocorticoid effects on the innate immune response. In zebrafish larvae, the migration of neutrophils towards a site of injury is inhibited upon glucocorticoid treatment, whereas migration of macrophages is glucocorticoid resistant. We show that wounding-induced increases in the expression of genes that encode neutrophil-specific chemoattractants (Il8 and Cxcl18b) are attenuated by the synthetic glucocorticoid beclomethasone, but that beclomethasone does not attenuate the induction of the genes encoding Ccl2 and Cxcl11aa, which are required for macrophage recruitment. RNA sequencing on FACS-sorted macrophages shows that the vast majority of the wounding-induced transcriptional changes in these cells are inhibited by beclomethasone, whereas only a small subset is glucocorticoid-insensitive. As a result, beclomethasone decreases the number of macrophages that differentiate towards a pro-inflammatory (M1) phenotype, which we demonstrated using a tnfa:eGFP-F reporter line and analysis of macrophage morphology. We conclude that differentiation and migration of macrophages are regulated independently, and that glucocorticoids leave the chemotactic migration of macrophages unaffected, but exert their anti-inflammatory effect on these cells by inhibiting their differentiation to an M1 phenotype. The resistance of macrophage-dominated diseases to glucocorticoid therapy can therefore not be attributed to an intrinsic insensitivity of macrophages to glucocorticoids.

Summary: In a zebrafish model for inflammation, glucocorticoids do not affect the migration of macrophages, but inhibit their differentiation towards an M1 phenotype, by strongly attenuating transcriptional responses in these cells.

Impact of Proinflammatory Cytokines on the Virulence of Uropathogenic Escherichia coli

The effect of a urinary tract infection on the host is a well-studied research field. However, how the host immune response affects uropathogenic Escherichia coli (CFT073) virulence is less studied. The aim of the present study was to investigate the impact of proinflammatory cytokine exposure on the virulence of uropathogenic Escherichia coli. We found that all tested proinflammatory cytokines (TNF-α, IL-1β, IL-6, IL-8 and IFN-γ) induced an increased CFT073 growth. We also found that biofilm formation and hemolytic activity was reduced in the presence of all proinflammatory cytokines. However, a reduction in siderophore release was only observed in the presence of IL-1β, IL-6 and IL-8. Real time-qPCR showed that all proinflammatory cytokines except TNF-α significantly increased genes associated with the iron acquisition system in CFT073. We also found that the proinflammatory cytokines induced significant changes in type-1 fimbriae, P-fimbriae and gluconeogenetic genes. Furthermore, we also showed, using a Caenorhabditis elegans (C. elegans) killing assay that all cytokines decreased the survival of C. elegans worms significantly. Taken together, our findings show that proinflammatory cytokines have the ability to alter the virulence traits of UPEC.

Human renal fibroblasts are strong immunomobilizers during a urinary tract infection mediated by uropathogenic Escherichia coli

To prevent the onset of urosepsis and reduce mortality, a better understanding of how uropathogenic Escherichia coli (UPEC) manages to infiltrate the bloodstream through the kidneys is needed. The present study elucidates if human renal interstitial fibroblasts are part of the immune response limiting a UPEC infection, or if UPEC has the ability to modulate the fibroblasts for their own gain. Microarray results showed that upregulated genes were associated with an activated immune response. We also found that chemokines released from renal fibroblasts upon a UPEC infection could be mediated by LPS and triacylated lipoproteins activating the TLR2/1, TLR4, MAPK, NF-κB and PKC signaling pathways. Furthermore, UPEC was also shown to be able to adhere and invade renal fibroblasts, mediated by the P-fimbriae. Furthermore, it was found that renal fibroblasts were more immunoreactive than renal epithelial cells upon a UPEC infection. However, both renal fibroblasts and epithelial cells were equally efficient at inducing neutrophil migration. In conclusion, we have found that human renal fibroblasts can sense UPEC and mobilize a host response with neutrophil migration. This suggests that renal fibroblasts are not only structural cells that produce and regulate the extracellular matrix, but also highly immunoreactive cells.

Sex differences in lower urinary tract biology and physiology

Females and males differ significantly in gross anatomy and physiology of the lower urinary tract, and these differences are commonly discussed in the medical and scientific literature. However, less attention is dedicated to investigating the varied development, function, and biology between females and males on a cellular level. Recognizing that cell biology is not uniform, especially in the lower urinary tract of females and males, is crucial for providing context and relevance for diverse fields of biomedical investigation. This review serves to characterize the current understanding of biological sex differences between female and male lower urinary tracts, while identifying areas for future research. First, the differences in overall cell populations are discussed in the detrusor smooth muscle, urothelium, and trigone. Second, the urethra is discussed, including anatomic discussions of the female and male urethra followed by discussions of cellular differences in the urothelial and muscular layers. The pelvic floor is then reviewed, followed by an examination of the sex differences in hormonal regulation, the urinary tract microbiome, and the reticuloendothelial system. Understanding the complex and dynamic development, anatomy, and physiology of the lower urinary tract should be contextualized by the sex differences described in this review.

Host-Derived Nitric Oxide and Its Antibacterial Effects in the Urinary Tract

Urinary tract infection (UTI) is one of the most common bacterial infections in humans, and the majority are caused by uropathogenic Escherichia coli (UPEC). The rising antibiotic resistance among UPEC and the frequent failure of antibiotics to effectively treat recurrent UTI and catheter-associated UTI motivate research on alternative ways of managing UTI. Abundant evidence indicates that the toxic radical nitric oxide (NO), formed by activation of the inducible nitric oxide synthase, plays an important role in host defence to bacterial infections, including UTI. The major source of NO production during UTI is from inflammatory cells, especially neutrophils, and from the uroepithelial cells that are known to orchestrate the innate immune response during UTI. NO and reactive nitrogen species have a wide range of antibacterial targets, including DNA, heme proteins, iron-sulfur clusters, and protein thiol groups. However, UPEC have acquired a variety of defence mechanisms for protection against NO, such as the NO-detoxifying enzyme flavohemoglobin and the NO-tolerant cytochrome bd-I respiratory oxidase. The cytotoxicity of NO-derived intermediates is nonspecific and may be detrimental to host cells, and a balanced NO production is crucial to maintain the tissue integrity of the urinary tract. In this review, we will give an overview of how NO production from host cells in the urinary tract is activated and regulated, the effect of NO on UPEC growth and colonization, and the ability of UPEC to protect themselves against NO. We also discuss the attempts that have been made to develop NO-based therapeutics for UTI treatment.

Association between interleukin 8-receptor gene (CXCR1 and CXCR2) polymorphisms and urinary tract infection: Evidence from 4097 subjects

AIM

The aim of this study was to determine whether a correlation exists between interleukin-8 receptor polymorphisms and urinary tract infection (UTI) susceptibility.

METHODS

We systematically searched electronic databases including PubMed, Embase, China National Knowledge Infrastructure, and Web of Science up to 5 November 2017 to select appropriate studies that focused on C-X-C chemokine receptor type 1 and/or 2 (CXCR1, CXCR2) polymorphisms with susceptibility to UTI. Eight case-control studies including 2085 patients with UTI and 2012 controls were enrolled in this study. Seven studies of CXCR1 rs2234671 and two studies of rs3138086 were included in the meta-analyses. Pooled odds ratio (OR) and corresponding 95% confidence interval (CI) were synthesized using fixed-effects or random-effects model according to heterogeneity.

RESULTS

No significant correlations were found between CXCR1 rs2234671 and rs3138086 polymorphisms and UTI susceptibility. However, subgroup analysis showed that rs2234671 was associated with an increased risk of UTI under allelic comparisons (C vs. G, OR = 1.95, 95% CI = 1.07-3.55), heterozygous model (GC vs. GG, OR = 1.93, 95% CI = 1.06-3.50), and dominant model (GC + CC vs. GG, OR = 1.98, 95% CI = 1.07-3.69) in children, especially in paediatric patients with acute pyelonephritis (allelic, OR = 2.43, 95% CI = 1.28-4.60; heterozygous, OR = 2.40, 95% CI = 1.24-4.62; dominant, OR = 2.48, 95% CI = 1.26-4.88). Furthermore, these results remained the same after eliminating paediatric patients with vesicoureteral reflux.

CONCLUSION

CXCR1 rs2234671 polymorphism might be associated with an increased risk of UTI in children.

Activation of the NLRP3 Inflammasome Pathway by Uropathogenic Escherichia coli Is Virulence Factor-Dependent and Influences Colonization of Bladder Epithelial Cells

The NLRP3 inflammasome and IL-1β release have recently been suggested to be important for the progression of urinary tract infection (UTI). However, much is still unknown regarding the interaction of UPEC and the NLRP3 inflammasome. The purpose of this study was to elucidate what virulence factors uropathogenic Escherichia coli (UPEC) use to modulate NLRP3 inflammasome activation and subsequent IL-1β release and the role of NLRP3 for UPEC colonization of bladder epithelial cells. The bladder epithelial cell line 5637, CRISPR/Cas9 generated NLRP3, caspase-1 and mesotrypsin deficient cell lines and transformed primary bladder epithelial cells (HBLAK) were stimulated with UPEC isolates and the non-pathogenic MG1655 strain. We found that the UPEC strain CFT073, but not MG1655, induced an increased caspase-1 activity and IL-1β release from bladder epithelial cells. The increase was shown to be mediated by α-hemolysin activation of the NLRP3 inflammasome in an NF-κB-independent manner. The effect of α-hemolysin on IL-1β release was biphasic, initially suppressive, later inductive. Furthermore, the phase-locked type-1-fimbrial ON variant of CFT073 inhibited caspase-1 activation and IL-1β release. In addition, the ability of CFT073 to adhere to and invade NLRP3 deficient cells was significantly reduced compare to wild-type cells. The reduced colonization of NLRP3-deficient cells was type-1 fimbriae dependent. In conclusion, we found that the NLRP3 inflammasome was important for type-1 fimbriae-dependent colonization of bladder epithelial cells and that both type-1 fimbriae and α-hemolysin can modulate the activity of the NLRP3 inflammasome.

Interleukin-6/Stat3 signaling has an essential role in the host antimicrobial response to urinary tract infection

The signaling networks regulating antimicrobial activity during urinary tract infection (UTI) are incompletely understood. Interleukin-6 (IL-6) levels increase with UTI severity, but the specific contributions of IL-6 to host immunity against bacterial uropathogens are unknown. To clarify this we tested whether IL-6 activates the Stat3 transcription factor, to drive a program of antimicrobial peptide gene expression in infected urothelium during UTI. Transurethral inoculation of uropathogenic Escherichia coli led to IL-6 secretion, urothelial Stat3 phosphorylation, and activation of antimicrobial peptide transcription, in a Toll-like receptor 4-dependent manner in a murine model of cystitis. Recombinant IL-6 elicited Stat3 phosphorylation in primary urothelial cells in vitro, and systemic IL-6 administration promoted urothelial Stat3 phosphorylation and antimicrobial peptide expression in vivo. IL-6 deficiency led to decreased urothelial Stat3 phosphorylation and antimicrobial peptide mRNA expression following UTI, a finding mirrored by conditional Stat3 deletion. Deficiency in IL-6 or Stat3 was associated with increased formation of intracellular bacterial communities, and exogenous IL-6 reversed this phenotype in IL-6 knockout mice. Moreover, chronic IL-6 depletion led to increased renal bacterial burden and severe pyelonephritis in C3H/HeOuJ mice. Thus, IL-6/Stat3 signaling drives a transcriptional program of antimicrobial gene expression in infected urothelium, with key roles in limiting epithelial invasion and ascending infection.

Bladder resident macrophages: Mucosal sentinels

Macrophages are instrumental in the response to infectious and noninfectious diseases, however, their role in the bladder is poorly understood. Indeed, the bladder is a mucosal tissue frequently overlooked in research, despite the prevalence of illnesses such as urinary tract infection and bladder cancer. Notably, bladder tissue macrophages are among the most populous resident immune cells in this organ and recent studies support that resident macrophages and infiltrating monocytes play nonredundant roles in response to infection, immunotherapy, and inflammation. Advancing our understanding of macrophage behavior in the bladder is complicated by the difficulty in obtaining tissue-resident cells. Surmounting this challenge, however, for a greater understanding of macrophage ontology, impact on innate and adaptive immunity, and regulation of homeostasis, will ultimately contribute to better therapies for common afflictions of the bladder.

Testing an association between TLR4 and CXCR1 gene polymorphisms with susceptibility to urinary tract infection in type 2 diabetes in north Indian population

BACKGROUND

Genetic variations of Toll like receptor 4 (TLR4) and CXC-chemokine receptor type1 (CXCR1), the key elements of innate immune system and their association with urinary tract infection (UTI) were studied in general population. In present study we investigate genetic variation of these genes in diabetic patients (3 to 4 times higher prevalence of UTI in comparison to general population).

METHODS

A total 1100 subjects (318 diabetic patients with UTI, 324 diabetic patients without UTI, 200 non-diabetic UTI patients and 260 age matched healthy control) were enrolled in the study. SNPs of TLR4 rs4986790, rs4986791 and CXCR1 rs2234671 was assessed by PCR-RFLP and PCR-SSP respectively.

RESULTS

Statistical analysis revealed that A/G genotype and G allele of TLR4 rs4986790 are significantly associated with UTI in both diabetics and nondiabetic patients in comparison to healthy control. Similarly CT genotype and T allele of TLR4 rs4986791 are also significantly associated with UTI in both groups. We also found that prevalence of A/G genotype of TLR4 rs4986790 and CT genotype of TLR4 rs4986791 are significantly higher in patients of diabetes with UTI in comparison to diabetic patients without UTI. We did not find any association of CXCR1 rs2234671 polymorphism with UTI by comparing with any group.

CONCLUSION

We found that TLR4 rs4986790 and rs4986791 gene polymorphism is a risk for UTI development in both diabetic and nondiabetic patients in north Indian population.

Susceptibility to Urinary Tract Infection: Benefits and Hazards of the Antibacterial Host Response

A paradigm shift is needed to improve and personalize the diagnosis of infectious disease and to select appropriate therapies. For many years, only the most severe and complicated bacterial infections received more detailed diagnostic and therapeutic attention as the efficiency of antibiotic therapy has guaranteed efficient treatment of patients suffering from the most common infections. Indeed, treatability almost became a rationale not to analyze bacterial and host parameters in these larger patient groups. Due to the rapid spread of antibiotic resistance, common infections like respiratory tract- or urinary-tract infections (UTIs) now pose new and significant therapeutic challenges. It is fortunate and timely that infectious disease research can offer such a wealth of new molecular information that is ready to use for the identification of susceptible patients and design of new suitable therapies. Paradoxically, the threat of antibiotic resistance may become a window of opportunity, by encouraging the implementation of new diagnostic and therapeutic approaches. The frequency of antibiotic resistance is rising rapidly in uropathogenic organisms and the molecular and genetic understanding of UTI susceptibility is quite advanced. More bold translation of the new molecular diagnostic and therapeutic tools would not just be possible but of great potential benefit in this patient group. This chapter reviews the molecular basis for susceptibility to UTI, including recent advances in genetics, and discusses the consequences for diagnosis and therapy. By dissecting the increasingly well-defined molecular interactions between bacteria and host and the molecular features of excessive bacterial virulence or host-response malfunction, it is becoming possible to isolate the defensive from the damaging aspects of the host response. Distinguishing "good" from "bad" inflammation has been a long-term quest of biomedical science and in UTI, patients need the "good" aspects of the inflammatory response to resist infection while avoiding the "bad" aspects, causing chronicity and tissue damage.

Expression of CXCR1 (IL-8 receptor A) in splenic, peritoneal macrophages and resident bone marrow cells after acute live or heat killed Staphylococcus aureus stimulation in mice

Literature reveals that interaction with live Staphylococcus aureus (S. aureus) or heat killed S. aureus (HKSA) promotes secretion of CXCL-8 or interleukin-8 (IL-8) from leukocytes, however, the expressions of CXCR1 in murine splenic (SPM), peritoneal macrophages (PM) and resident fresh bone marrow cells (FBMC) have not been identified. Currently, very few studies are available on the functional characterization of CXCR1 in mouse macrophage subtypes and its modulation in relation to acute S. aureus infection. SPM, PM and FBMCs were infected with viable S. aureus or stimulated with HKSA in presence and absence of anti-CXCR1 antibody in this study. We reported here that CXCR1 was not constitutively expressed by macrophage subtypes and the receptor was induced only after S. aureus stimulation. The CXCR1 band was found specific as we compared with human polymorphonuclear neutrophils (PMNs) as a positive control (data not shown). Although, we did not show that secreted IL-8 from S. aureus-infected macrophages promotes migration of PMNs. Blocking of cell surface CXCR1 decreases the macrophage's ability to clear staphylococcal infection, attenuates proinflammatory cytokine production and the increased catalase and decreased superoxide dismutase (SOD) enzymes of the bacteria might indicate their role in scavenging macrophage derived hydrogen peroxide (H₂O₂). The decreased levels of cytokines due to CXCR1 blockade before S. aureus infection appear to regulate the killing of bacteria by destroying H₂O₂ and nitric oxide (NO). Moreover, functional importance of macrophage subpopulation heterogeneity might be important in designing new effective approaches to limit S. aureus infection induced inflammation and cytotoxicity.

Elevated CXC chemokines in urine noninvasively discriminate OAB from UTI

Overlapping symptoms of overactive bladder (OAB) and urinary tract infection (UTI) often complicate the diagnosis and contribute to overprescription of antibiotics. Inflammatory response is a shared characteristic of both UTI and OAB and here we hypothesized that molecular differences in inflammatory response seen in urine can help discriminate OAB from UTI. Subjects in the age range of (20-88 yr) of either sex were recruited for this urine analysis study. Urine specimens were available from 62 UTI patients with positive dipstick test before antibiotic treatment. Six of these patients also provided urine after completion of antibiotic treatment. Subjects in cohorts of OAB (n = 59) and asymptomatic controls (n = 26) were negative for dipstick test. Urinary chemokines were measured by MILLIPLEX MAP Human Cytokine/Chemokine Immunoassay and their association with UTI and OAB was determined by univariate and multivariate statistics. Significant elevation of CXCL-1, CXCL-8 (IL-8), and CXCL-10 together with reduced levels for a receptor antagonist of IL-1A (sIL-1RA) were seen in UTI relative to OAB and asymptomatic controls. Elevated CXCL-1 urine levels predicted UTI with odds ratio of 1.018 and showed a specificity of 80.77% and sensitivity of 59.68%. Postantibiotic treatment, reduction was seen in all CXC chemokines with a significant reduction for CXCL-10. Strong association of CXCL-1 and CXCL-10 for UTI over OAB indicates mechanistic differences in signaling pathways driving inflammation secondary of infection in UTI compared with a lack of infection in OAB. Urinary chemokines highlight molecular differences in the paracrine signaling driving the overlapping symptoms of UTI and OAB.

Relationship of Urothelial Gene Expressions in Urine-Deprived Bladders of Renal Recipients With Posttransplant Urinary Infections

OBJECTIVE

In this study, we analyzed gene expression levels of apoptotic (Fas, FasL, Bcl-2, Bax) and survival (CXCR1, CXCR2, IL-8) signal pathways of the urine-deprived bladder tissues and the relation of urinary tract infections with these pathways.

MATERIAL AND METHODS

We included 37 patients admitted for renal transplantation between December 2009 and December 2012. Bladder mucosal samples were obtained at the time of transplantation and 6-8 weeks posttransplantation, at the time of ureteral catheter removal. RNA extraction and cDNA synthesis were done using guanidium-thiocyanate and colon filter methods. Expression analysis was studied with quantitative real-time polymerase chain reaction optimized with ROX dye and internal control β-actin.

RESULTS

According to our findings Fas, FasL, Bcl-2, and Bax expression was higher in urine-deprived bladder samples than those in the posttransplant samples (P < .05). Although Fas, FasL, Bcl-2, and Bax expression levels increased in pretransplant samples, there was an increase in posttransplant bladder samples; however, this increase was not as marked as those of pretransplant samples. IL-8, CXCR1, and CXCR2 expression was decreased at the pretransplant samples and increased in posttransplant bladder samples.

CONCLUSIONS

We have found an upregulated apoptotic process and decreased survival signals at the urine-deprived bladder tissue. After transplantation, bladder tissue survival parameters were increased, demonstrating the importance of urinary flow for bladder tissue.

Are you experienced? Understanding bladder innate immunity in the context of recurrent urinary tract infection

PURPOSE OF REVIEW

Recurrent urinary tract infection (rUTI) is a serious clinical problem, yet effective therapeutic options are limited, especially against multidrug-resistant uropathogens. In this review, we explore the development of a clinically relevant model of rUTI in previously infected mice and review recent developments in bladder innate immunity that may affect susceptibility to rUTI.

RECENT FINDINGS

Chronic bladder inflammation during prolonged bacterial cystitis in mice causes bladder mucosal remodelling that sensitizes the host to rUTI. Although constitutive defenses help prevent bacterial colonization of the urinary bladder, once infection occurs, induced cytokine and myeloid cell responses predominate and the balance of immune cell defense and bladder immunopathology is critical for determining disease outcome, in both naïve and experienced mice. In particular, the maintenance of the epithelial barrier appears to be essential for preventing severe infection.

SUMMARY

The innate immune response plays a key role in determining susceptibility to rUTI. Future studies should be directed towards understanding how the innate immune response changes as a result of bladder mucosal remodelling in previously infected mice, and validating these findings in human clinical specimens. New therapeutics targeting the immune response should selectively target the induced innate responses that cause bladder immunopathology, while leaving protective defenses intact.

Innate immunity and genetic determinants of urinary tract infection susceptibility

Purpose of review

Urinary tract infections (UTIs) are common, dangerous and interesting. Susceptible individuals experience multiple, often clustered episodes, and in a subset of patients, infections progress to acute pyelonephritis (APN), sometimes accompanied by uro-sepsis. Others develop asymptomatic bacteriuria (ABU). Here, we review the molecular basis for these differences, with the intention to distinguish exaggerated host responses that drive disease from attenuated responses that favour protection and to highlight the genetic basis for these extremes, based on knock-out mice and clinical studies.

Recent findings

The susceptibility to UTI is controlled by specific innate immune signalling and by promoter polymorphisms and transcription factors that modulate the expression of genes controlling these pathways. Gene deletions that disturb innate immune activation either favour asymptomatic bacteriuria or create acute morbidity and disease. Promoter polymorphisms and transcription factor variants affecting those genes are associated with susceptibility in UTI-prone patients.

Summary

It is time to start using genetics in UTI-prone patients, to improve diagnosis and to assess the risk for chronic sequels such as renal malfunction, hypertension, spontaneous abortions, dialysis and transplantation. Furthermore, the majority of UTI patients do not need follow-up, but for lack of molecular markers, they are unnecessarily investigated.

Type 1 Diabetes Prone NOD Mice Have Diminished Cxcr1 mRNA Expression in Polymorphonuclear Neutrophils and CD4+ T Lymphocytes

In humans, CXCR1 and CXCR2 are two homologous proteins that bind ELR+ chemokines. Both receptors play fundamental roles in neutrophil functions such as migration and reactive oxygen species production. Mouse Cxcr1 and Cxcr2 genes are located in an insulin-dependent diabetes genetic susceptibility locus. The non obese diabetic (NOD) mouse is a spontaneous well-described animal model for insulin-dependent type 1 diabetes. In this disease, insulin deficiency results from the destruction of insulin-producing beta cells by autoreactive T lymphocytes. This slow-progressing disease is dependent on both environmental and genetic factors. Here, we report descriptive data about the Cxcr1 gene in NOD mice. We demonstrate decreased expression of mRNA for Cxcr1 in neutrophils and CD4+ lymphocytes isolated from NOD mice compared to other strains, related to reduced NOD Cxcr1 gene promoter activity. Looking for Cxcr1 protein, we next analyze the membrane proteome of murine neutrophils by mass spectrometry. Although Cxcr2 protein is clearly found in murine neutrophils, we did not find evidence of Cxcr1 peptides using this method. Nevertheless, in view of recently-published experimental data obtained in NOD mice, we argue for possible Cxcr1 involvement in type 1 diabetes pathogenesis.

Macrophages Subvert Adaptive Immunity to Urinary Tract Infection

Urinary tract infection (UTI) is one of the most common bacterial infections with frequent recurrence being a major medical challenge. Development of effective therapies has been impeded by the lack of knowledge of events leading to adaptive immunity. Here, we establish conclusive evidence that an adaptive immune response is generated during UTI, yet this response does not establish sterilizing immunity. To investigate the underlying deficiency, we delineated the naïve bladder immune cell compartment, identifying resident macrophages as the most populous immune cell. To evaluate their impact on the establishment of adaptive immune responses following infection, we measured bacterial clearance in mice depleted of either circulating monocytes, which give rise to macrophages, or bladder resident macrophages. Surprisingly, mice depleted of resident macrophages, prior to primary infection, exhibited a nearly 2-log reduction in bacterial burden following secondary challenge compared to untreated animals. This increased bacterial clearance, in the context of a challenge infection, was dependent on lymphocytes. Macrophages were the predominant antigen presenting cell to acquire bacteria post-infection and in their absence, bacterial uptake by dendritic cells was increased almost 2-fold. These data suggest that bacterial uptake by tissue macrophages impedes development of adaptive immune responses during UTI, revealing a novel target for enhancing host responses to bacterial infection of the bladder.

Urinary tract infection is a common infection with a high propensity for recurrence. The majority of infections are caused by uropathogenic E. coli, a growing public health concern with increasing prevalence of antibiotic resistant strains. Finding therapeutic options that circumvent the need for antibiotics, while boosting patients’ immune response to infection is desirable to counteract further increases in antibiotic resistance and to provide long-lasting resistance to infection. Currently, little is known about how adaptive immune responses, which typically prevent recurrent infection in other organs, arise from the bladder during urinary tract infection. Here, we investigated the initial interactions between immune cell populations of the bladder and uropathogenic E. coli, finding that macrophages are the principal cell population to engulf bacteria. Interestingly, these same cells appear to inhibit the development of adaptive immunity to the bacteria, as their depletion, prior to primary infection, results in a stronger immune response during bacterial challenge. We found that in the absence of macrophages, dendritic cells, which are the most potent initiators of adaptive immunity, are able to take up more bacteria for presentation. Our study has revealed a mechanism in which specific immune cells may act in a manner detrimental to host immunity.

Urinary tract infection of mice to model human disease: Practicalities, implications and limitations

Urinary tract infections (UTIs) are among the most common bacterial infections in humans. Murine models of human UTI are vital experimental tools that have helped to elucidate UTI pathogenesis and advance knowledge of potential treatment and infection prevention strategies. Fundamentally, several variables are inherent in different murine models, and understanding the limitations of these variables provides an opportunity to understand how models may be best applied to research aimed at mimicking human disease. In this review, we discuss variables inherent in murine UTI model studies and how these affect model usage, data analysis and data interpretation. We examine recent studies that have elucidated UTI host-pathogen interactions from the perspective of gene expression, and review new studies of biofilm and UTI preventative approaches. We also consider potential standards for variables inherent in murine UTI models and discuss how these might expand the utility of models for mimicking human disease and uncovering new aspects of pathogenesis.

Novel Human Cytomegalovirus Viral Chemokines, vCXCL-1s, Display Functional Selectivity for Neutrophil Signaling and Function

Human CMV (HCMV) uses members of the hematopoietic system including neutrophils for dissemination throughout the body. HCMV encodes a viral chemokine, vCXCL-1, that is postulated to attract neutrophils for dissemination within the host. The gene encoding vCXCL-1, UL146, is one of the most variable genes in the HCMV genome. Why HCMV has evolved this hypervariability and how this affects the virus' dissemination and pathogenesis is unknown. Because the vCXCL-1 hypervariability maps to important binding and activation domains, we hypothesized that vCXCL-1s differentially activate neutrophils, which could contribute to HCMV dissemination, pathogenesis, or both. To test whether these viral chemokines affect neutrophil function, we generated vCXCL-1 proteins from 11 different clades from clinical isolates from infants infected congenitally with HCMV. All vCXCL-1s were able to induce calcium flux at a concentration of 100 nM and integrin expression on human peripheral blood neutrophils, despite differences in affinity for the CXCR1 and CXCR2 receptors. In fact, their affinity for CXCR1 or CXCR2 did not correlate directly with chemotaxis, G protein-dependent and independent (β-arrestin-2) activation, or secondary chemokine (CCL22) expression. Our data suggest that vCXCL-1 polymorphisms affect the binding affinity, receptor usage, and differential peripheral blood neutrophil activation that could contribute to HCMV dissemination and pathogenesis.

Decreased Expression of Innate Immunity-Related Genes in Peripheral Blood Mononuclear Cells from Patients with IgG4-Related Disease

Background

IgG4-related disease (IgG4-RD) is a new clinical entity of unknown etiology characterized by elevated serum IgG4 and tissue infiltration by IgG4-positive plasma cells. Although aberrancies in acquired immune system functions, including increases in Th2 and Treg cytokines observed in patients with IgG4-RD, its true etiology remains unclear. To investigate the pathogenesis of IgG4-RD, this study compared the expression of genes related to innate immunity in patients with IgG4-RD and healthy controls.

Materials and Methods

Peripheral blood mononuclear cells (PBMCs) were obtained from patients with IgG4-RD before and after steroid therapy and from healthy controls. Total RNA was extracted and DNA microarray analysis was performed in two IgG4-RD patients to screen for genes showing changes in expression. Candidate genes were validated by real-time RT-PCR in 27 patients with IgG4-RD and 13 healthy controls.

Results

DNA microarray analysis identified 21 genes that showed a greater than 3-fold difference in expression between IgG4-RD patients and healthy controls and 30 genes that showed a greater than 3-fold change in IgG4-RD patients following steroid therapy. Candidate genes related to innate immunity, including those encoding Charcot–Leyden crystal protein (CLC), membrane-spanning 4-domain subfamily A member 3 (MS4A3), defensin alpha (DEFA) 3 and 4, and interleukin-8 receptors (IL8R), were validated by real-time RT-PCR. Expression of all genes was significantly lower in IgG4-RD patients than in healthy controls. Steroid therapy significantly increased the expression of DEFA3, DEFA4 and MS4A3, but had no effect on the expression of CLC, IL8RA and IL8RB.

Conclusions

The expression of genes related to allergy or innate immunity, including CLC, MS4A3, DEFA3, DEFA4, IL8RA and IL8RB, was lower in PBMCs from patients with IgG4-RD than from healthy controls. Although there is the limitation in the number of patients applied in DNA microarray, impaired expression of genes related to innate immunity may be involved in the pathogenesis of IgG4-RD as well as in abnormalities of acquired immunity.

Urinary tract infections in children: knowledge updates and a salute to the future

1. Evaluating and treating bladder and bowel dysfunction are critical in reducing the risk of urinary tract infections (UTIs). 2. The pathogenesis of Escherichia coli infections reveals that quiescent intracellular reservoirs may be antibiotic-protected sources of recurrent infections.

OBJECTIVES

1. Review the documentation of UTI and the importance of the urine culture. 2. Understand the controversy over imaging and management of febrile UTIs in children. 3. Recognize the risk factors for recurrent UTIs and strategies for intervention. 4. Update information on the pathogenesis of E coli UTIs.

Association of interleukin-10 gene promoter polymorphisms with susceptibility to acute pyelonephritis in children

Interleukin-10 (IL-10) is a potent inhibitor of leukocyte chemotaxis, bacterial killing in phagocytes and synthesis of pro-inflammatory cytokines and chemokines, and recent studies have suggested an important role for this immunoregulatory cytokine in the pathogenesis of urinary tract infections (UTIs). Therefore, the gene encoding IL-10 (IL10) is an attractive candidate for association studies attempting to identify susceptibility genes conferring risk of UTIs. In this case-control study, we aimed to investigate the association of single nucleotide polymorphisms (SNPs) in the promoter region of IL10 with acute pyelonephritis in the Slovak population. Polymerase chain reaction with sequence-specific primers was used to analyse IL10 -1082A/G (rs1800896), -819C/T (rs1800871) and -592C/A (rs1800872) SNPs in 147 children with acute pyelonephritis and 215 healthy controls. Comparison of patients with healthy controls using the logistic regression analysis revealed significantly increased risk of developing recurrent attacks of acute pyelonephritis for -1082 G allele in a dominant genetic model GG (GG + AG vs. AA, P = 0.019, odds ratio (OR) = 2.26). A similar tendency was also found when the recurrent acute pyelonephritis subgroup was compared to episodic pyelonephritis cases (GG + AG vs. AA, P = 0.009, OR = 3.38). In conclusion, our results suggest that IL10 -1082 A/G SNP is a susceptibility factor for development of recurrent attacks of acute pyelonephritis.

Haplotype analysis of interleukin-8 gene polymorphisms in chronic and aggressive periodontitis

Objectives. Periodontitis is an inflammatory disease characterized by connective tissue loss and alveolar bone destruction. Interleukin-8 (IL8) is important in the regulation of the immune response. The aim of this study was to analyze four polymorphisms in the IL8 gene in relation to chronic (CP) and aggressive (AgP) periodontitis. Methods. A total of 492 unrelated subjects were included in this case-control association study. Genomic DNA of 278 patients with CP, 58 patients with AgP, and 156 controls were genotyped, using the 5′ nuclease TaqMan assay, for IL8 (rs4073, rs2227307, rs2227306, and rs2227532) gene polymorphisms. Subgingival bacterial colonization was investigated by the DNA-microarray detection kit in a subgroup of subjects (N = 247). Results. Allele and genotype frequencies of all investigated IL8 polymorphisms were not significantly different between the subjects with CP and/or AgP and controls (P > 0.05). Nevertheless, the A(−251)/T(+396)/T(+781) and T(−251)/G(+396)/C(+781) haplotypes were significantly less frequent in patients with CP (2.0% versus 5.1%, P < 0.02, OR = 0.34, 95% CI: 0.15–0.78, resp., 2.0% versus 4.5%, P < 0.05, OR = 0.41, 95% CI: 0.18–0.97) than in controls. Conclusions. Although none of the investigated SNPs in the IL8 gene was individually associated with periodontitis, some haplotypes can be protective against CP in the Czech population.

Slit2 prevents neutrophil recruitment and renal ischemia-reperfusion injury

Neutrophils recruited to the postischemic kidney contribute to the pathogenesis of ischemia-reperfusion injury (IRI), which is the most common cause of renal failure among hospitalized patients. The Slit family of secreted proteins inhibits chemotaxis of leukocytes by preventing activation of Rho-family GTPases, suggesting that members of this family might modulate the recruitment of neutrophils and the resulting IRI. Here, in static and microfluidic shear assays, Slit2 inhibited multiple steps required for the infiltration of neutrophils into tissue. Specifically, Slit2 blocked the capture and firm adhesion of human neutrophils to inflamed vascular endothelial barriers as well as their subsequent transmigration. To examine whether these observations were relevant to renal IRI, we administered Slit2 to mice before bilateral clamping of the renal pedicles. Assessed at 18 hours after reperfusion, Slit2 significantly inhibited renal tubular necrosis, neutrophil and macrophage infiltration, and rise in plasma creatinine. In vitro, Slit2 did not impair the protective functions of neutrophils, including phagocytosis and superoxide production, and did not inhibit neutrophils from killing the extracellular pathogen Staphylococcus aureus. In vivo, administration of Slit2 did not attenuate neutrophil recruitment or bacterial clearance in mice with ascending Escherichia coli urinary tract infections and did not increase the bacterial load in the livers of mice infected with the intracellular pathogen Listeria monocytogenes. Collectively, these results suggest that Slit2 may hold promise as a strategy to combat renal IRI without compromising the protective innate immune response.

Cxcl8 (IL-8) mediates neutrophil recruitment and behavior in the zebrafish inflammatory response

Neutrophils play a pivotal role in the innate immune response. The small cytokine CXCL8 (also known as IL-8) is known to be one of the most potent chemoattractant molecules that, among several other functions, is responsible for guiding neutrophils through the tissue matrix until they reach sites of injury. Unlike mice and rats that lack a CXCL8 homolog, zebrafish has two distinct CXCL8 homologs: Cxcl8-l1 and Cxcl8-l2. Cxcl8-l1 is known to be upregulated under inflammatory conditions caused by bacterial or chemical insult but until now the role of Cxcl8s in neutrophil recruitment has not been studied. In this study we show that both Cxcl8 genes are upregulated in response to an acute inflammatory stimulus, and that both are crucial for normal neutrophil recruitment to the wound and normal resolution of inflammation. Additionally, we have analyzed neutrophil migratory behavior through tissues to the site of injury in vivo, using open-access phagocyte tracking software PhagoSight. Surprisingly, we observed that in the absence of these chemokines, the speed of the neutrophils migrating to the wound was significantly increased in comparison with control neutrophils, although the directionality was not affected. Our analysis suggests that zebrafish may possess a subpopulation of neutrophils whose recruitment to inflamed areas occurs independently of Cxcl8 chemokines. Moreover, we report that Cxcl8-l2 signaled through Cxcr2 for inducing neutrophil recruitment. Our study, therefore, confirms the zebrafish as an excellent in vivo model to shed light on the roles of CXCL8 in neutrophil biology.

Global H3K4me3 genome mapping reveals alterations of innate immunity signaling and overexpression of JMJD3 in human myelodysplastic syndrome CD34+ cells

The molecular bases of myelodysplastic syndromes (MDS) are not fully understood. Trimethylated histone 3 lysine 4 (H3K4me3) is present in promoters of actively transcribed genes and has been shown to be involved in hematopoietic differentiation. We performed a genome-wide H3K4me3 CHIP-Seq (chromatin immunoprecipitation coupled with whole genome sequencing) analysis of primary MDS bone marrow (BM) CD34+ cells. This resulted in the identification of 36 genes marked by distinct higher levels of promoter H3K4me3 in MDS. A majority of these genes are involved in nuclear factor (NF)-κB activation and innate immunity signaling. We then analyzed expression of histone demethylases and observed significant overexpression of the JmjC-domain histone demethylase JMJD3 (KDM6b) in MDS CD34+ cells. Furthermore, we demonstrate that JMJD3 has a positive effect on transcription of multiple CHIP-Seq identified genes involved in NF-κB activation. Inhibition of JMJD3 using shRNA in primary BM MDS CD34+ cells resulted in an increased number of erythroid colonies in samples isolated from patients with lower-risk MDS. Taken together, these data indicate the deregulation of H3K4me3 and associated abnormal activation of innate immunity signals have a role in the pathogenesis of MDS and that targeting these signals may have potential therapeutic value in MDS.

Can postpyelonephritic renal scarring be prevented?

Pyelonephritis in childhood may, in the worst cases, lead to long-term cardiovascular morbidity due to tubulointerstitial renal scarring. Renal damage is the end result of an interplay between (1) urinary tract anatomy and function, (2) bacterial virulence factors, and (3) the host innate immune system, which on the one hand manages bacterial clearance, but on the other causes tubulointerstitial inflammation, which underlies the renal scarring. It is unclear how common postpyelonephritic scarring is, and how many of the "scars" in fact represent congenital renal hypoplasia. We do, however, know that some situations have an increased risk for scars, i.e., large renal-uptake defects on initial renal scintigraphy or pyelonephritis in young girls with dilating vesicoureteral reflux. It seems logical that antiinflammatory or antioxidant therapy given concomitantly with antibiotics should lower the risk of postpyelonephritic scarring. Animal studies give some support to this idea, but research on humans has been surprisingly scant. In this issue of Pediatric Nephrology, we publish a study that indicates that antioxidant therapy with vitamin A or E given to children with pyelonephritis may indeed lower the risk for renal scarring. This is a track that needs to be pursued further.

Epithelial G protein-coupled receptor kinases regulate the initial inflammatory response during mycobacterial infection

The interaction between mycobacteria and epithelium is unexplored, but may determine the outcome of the infection. We have analyzed the role of two G protein-coupled receptors, CXCR1 and CXCR2 that are important regulators of many pulmonary diseases. We found that mycobacteria significantly increased the expression of both CXCR1 and CXCR2 on alveolar epithelial cells and both receptors were found to be important for neutrophil diapedesis across primary endothelial cells towards infected mucosa. Mycobacteria, lipoarabinomannan or 19-kDa glycolipoprotein up-regulated the inhibitory G protein-coupled receptor kinase (GRK)2, while GRK3 was less affected. Mycobacteria-induced GRK2 up-regulation decreased chemokine transcription and secretion thereby affecting the neutrophil recruitment to infected mucosa. These events were completely abolished by blocking these receptors prior to infection as the blocking increased epithelial immune responses. We have identified novel interactions occurring in the initial phase of mycobacterial infections by which mycobacterial manipulate epithelial inflammatory responses.